1. Field of the Invention
The present invention relates to a language input method, and more specifically, to a method for inputting Mandarin Phonetic Symbols using a keypad.
2. Description of the Prior Art
Every written character in Chinese can be represented by a phonetic representation of the character. Of all Chinese dialects, Mandarin Chinese is most widely spoken. Accordingly, there are many phonetic systems available for representing Mandarin pronunciations of Chinese characters. One such phonetic system that is primarily used in Taiwan is called Mandarin Phonetic Symbols (MPS). The MPS phonetic system consists of 37 symbols that can be combined to represent every phonetic sound spoken in Mandarin.
When using electronic devices such as cellular phones or personal digital assistants (PDAs), the 37 symbols are usually mapped to keys on an input keypad. By clicking on appropriate keys, Chinese characters can be entered into the electronic device.
Please refer to FIG. 1A. FIG. 1A is an electronic device 10 with a keypad 13 used to input MPS according to the prior art. FIG. 1A shows 12 standard keys present on a normal telephone, namely “1-9”, “*”, “0”, and “#”. Notice, however, that only 10 of the 12 keys are used for mapping MPS. Each character in the Chinese language can be represented by the combination of one, two, or three Mandarin Phonetic Symbols. When three symbols are used to represent a Chinese character, a first, a middle, and a third symbol are used. Moreover, the middle symbol is always, “”, “”, or “”, which are found on a “#” key 18 of FIG. 1A. The “” symbol is never used as a middle symbol, and is not considered as a possibility when the “#” key 18 is used to enter a middle symbol.
To enter a Chinese character that is represented by three symbols, three keys would have to be pressed. For example, the Chinese character “” would be entered using “”, “”, and “”. To accomplish this, a “1” key 14, the “#” key 18, and a “9” key 16 of the keypad 13 would be pressed, respectively.
Unfortunately, mapping 37 symbols to only 10 keys of a keypad 13 creates many problems when entering Chinese characters. The problem results from each key having three or four symbols mapped to it. Because of this, many phonetic combinations are possible when keys on the keypad 13 are pressed. For example, when the Chinese character “” is entered by pressing the “1” key 14, the “#” key 18, and the “9” key 16 of the keypad 13, other combinations of symbols exist other than “”, “”, and “”.
“1” key 14: “”, “”, “”, and “”
4 possibilities;
“#” key 18: “”, “”, and “”
3 possibilities; and
“9” key 16:“”, “”, “”, and “”
4 possibilities.
As shown above, pressing the “1” key 14, the “#” key 18, and the “9” key 16 generates 4×3×4=48 combinations. This means that a user of the electronic device 10 would then have to choose the correct combination of symbols out of the 48 combinations generated. Clearly this is not desirable, as inputting Chinese characters is severely delayed by the enormous amount of combinations to choose from. Moreover, it is difficult to efficiently display 48 combinations on a screen of the electronic device.
Please refer to FIG. 1B. FIG. 1B is another electronic device 20 with a keypad 22 used to input MPS according to the prior art. The only difference between FIG. 1A and FIG. 1B is the symbols “”, “”, “”, and “” are located on a “0” key 24 on FIG. 1B instead of the “#” key 18 on FIG. 1A. Unfortunately, the arrangement of keys on FIG. 1B contains the same problem as that of FIG. 1A. That is, pressing three keys can generate a maximum of 48 combinations of symbols. Thus, a poor mapping of Mandarin Phonetic Symbols to keys on each of the keypads 13 and 22 limits the ease in which Chinese characters can be inputted using MPS.